Composting is an important practice for any organic polytunnel gardener. It simply involves using one of a number of methods to break down organic material into a friable, nutrient rich substance that can be used as a mulch or growing medium. Bokashi composting is one type of composting that you could consider. In this article, we’ll take a look at this method, and help you work out whether it is a good option for you.
What is Bokashi Composting?
Bokashi composting is a type of anaerobic composting that involves the use of a special bokashi inoculant. This special inoculant usually consists of either wheat germ, wheat bran or sawdust combined with molasses and ‘EM’ (effective microorganisms). Layers of this material are placed into an airtight, sealable container along with kitchen scraps. The materials are then left to ferment and break down over time.
The word ‘bokashi’ means ‘fermented organic matter’ in Japanese. It was developed in the early 1980s by a professor named Dr. Teuro Higa, who worked at Okinawa’s University of Ryukyus.
The fact that this is an anaerobic process means that it is very different to other forms of composting. Composting in a heap or bin, vermiculture (composting with the aid of special worms) or sheet-mulching/ composting in place are all aerobic processes. They involve allowing oxygen in. But bokashi composting is a fermentation process and oxygen is excluded as much as possible.
The differences in this technique mean that it has a different range of pros and cons. It also means that this method is utilised in a rather different way to the other composting methods mentioned above.
The Pros of Bokashi Composting
Organic material can be transformed into a nutrient rich substance using this method in just 10 days or so. The material can be buried in compost trenches in your garden, or added to other composting systems. (It is particularly beneficial when added to feed the worms in a wormery.)
The nutrient value of the substance created is higher than that of many other composts you can create.
The process also generates a highly nutritious liquid run off to use as a plant feed.
You can incorporate and recycle scraps that cannot usually be added to other composting systems, such as meat and dairy.
This process can be undertaken in small spaces – since materials are usually crammed into small buckets. So it is easily undertaken in a smaller domestic setting.
The Cons of Bokashi Composting
The material you create through this process is a fermented product – not a traditional compost. It cannot be added as a surface mulch but must be buried, or added to another composting system for further decomposition.
The process requires the purchase of special inoculants and an airtight receptacle (from which the fluid can be drained). It therefore may require more initial investment than some other, simpler methods. You will also likely have to continue to buy the inoculant over time.
Sourcing Materials for Your Bokashi System
If you decide that the bokashi process is a good idea for you, you will need:
A bucket or other container (ideally two). They must have well-sealing lids, and not be clear. You must also be able to drill a hole near the base of the bucket to add a tap to drain off the liquid, if the containers to not already have a drain and tap.
Compost activator/ inoculant. As mentioned above, this is usually a mix of wheat germ or wheat bran (sometimes called bokashi bran) or sawdust, with effective microorganisms and a molasses feed (or similar).
Finally, you will need some kitchen scraps to begin the fermentation process. You can add any of the green (nitrogen rich) kitchen scraps that you would usually add to your compost heap. However, you can also include things that you would not usually put into other composting systems, such as: meat and fish, dairy products, certain cooked foods etc.. There are, however, still some things that you cannot put into your bokashi bucket, such as meat bones, oils, too much liquid or, or course, anything inorganic and non-compostable.
Making your Own Bokashi Bucket
If you would like to go down the DIY route, you can make your own bokashi containers from 5 gallon buckets, or similar. You can use 5 gallon buckets that were originally used for other purposes, as long as they are lidded. There are a number of simple ways to ensure that you will be able to drain off the fluid from your DIY bokashi buckets. You will find a range of step by step tutorials and how-to guides to lead you through this simple process.
Making Your Own Bokashi ‘Bran’
While it is more usual to buy your bokashi bran/ bokashi inoculant, you can also create your own. If you have access to plenty of carbon rich sawdust, or even shredded card, you can buy EM1 (the effective microorganism mix) and add molasses and a little moisture to make your own. Some people also source microorganisms from nature themselves.
The bacteria you need belong primarily to three different strains: yeasts, (Saccharomyces spp.), bacteria that produce lactic acids (Lactobacillus spp.), and (phototrophic) purple non-sulfur bacteria (Rhodopseudomonas spp.) There are ways to ‘gather’ these microorganisms yourself to use in your bokashi system. But it is difficult to determine whether you have the right mix, and results can be patchy. As a general rule of thumb, the EM, molasses, water ratio should be 1:1:100.
If you are reluctant to go for more DIY options, buy kits that provide the vessel and the bokashi bran. That will allow you to get started.
Getting Started With a Bokashi System
Actually beginning the process of fermenting organic material with a bokashi system is simple. Once you have the bokashi bran (or other similar inoculant) you simply need to feed the microoganisms it contains with your kitchen scraps.
Do not open the container and let air in unless you are adding some scraps. When you do add some scraps, simply also add a little of the inoculant/ bokashi bran on top. It may also help to use a plate, or a piece of cardboard that fits the top of the bucket to push down and compress the materials within. This will help to make sure there are not any air pockets. It will also help you to make sure you can fit as much waste into the containers as possible.
Once the first of your buckets or vessels is full, simply leave it to one side for the fermentation to continue. You can then continue and add your kitchen scraps to the other container. Every couple of days or so, draw off the liquid that has run to the bottom of the full container. Dilute this liquid and you can use it as a beneficial plant feed.
After a couple of weeks, the transformation on the material in the first bucket will be complete. On the outside, you may see a little white mould, and note a fermented smell. But otherwise the material may look more or less the same. Under the surface, however, decomposition is well underway. The good bacteria will have got to work.
What To Do Next With Your Fermented Organic Material
This bokashi will break down much more quickly now when added to another composting system, or when buried in the soil in your garden. It will take only a short time (around 2 weeks in summer, around a month in winter) to fully break down in soil. This is unlike traditional composting systems, which will generally decompose materials in around 3-4 months.
As mentioned above, the mixture from your bokashi system will also be great to add to a wormery. The bokashi material will break down much more quickly, so the vermiculture composting process will be much quicker and more efficient.
Do you already have a bokashi composting system in place? Share any tips, suggestions or experiences to help others in the comments below. Would you recommend this system? Does it work well for you? Have you taken a DIY approach or chosen a kit? Let us know.
Elizabeth Waddington is a writer and green living consultant living in Scotland. Permaculture and sustainability are at the heart of everything she does, from designing gardens and farms around the world, to inspiring and facilitating positive change for small companies and individuals.
She also works on her own property, where she grows fruit and vegetables, keeps chickens and is working on the eco-renovation of an old stone barn.